1. Field of the Invention
The present invention relates to a multicasting network in an Asynchronous Transfer Mode(hereinafter called as xe2x80x9cATMxe2x80x9d) switching system and, more particularly, to a multicasting network in an ATM switching system for performing cell copying and routing using a space division switch.
2. Description of the Prior Art
In order to provide services like broadcasting, video, etc., a conventional ATM switch requires multicasting so that incoming cells are broadcasted to selected multiple outputs.
There are several methods for the design of multicasting. Among them, the method for providing each module(not shown) with a multicasting function, and the method for providing an extra copy network are frequently used.
FIG. 1 is a block diagram of a conventional ATM switch for performing the above-described multicasting procedure.
As illustrated in FIG. 1, a conventional ATM switch includes a copy network 10, a plurality of TNTs(Trunk Number Translators; hereinafter called as xe2x80x9cTNTs 20-1xcx9c20-nxe2x80x9d), and a route network 30.
The copy network 10 shown in FIG. 1 is a view illustrating an example of an operation, in which when a cell with destination addresses 0, 5, and 7 is inputted, a corresponding address loaded in a corresponding TNT is branched by a cell copy operation for multicasting, thereby being routed to the addresses 0, 5, and 7 of the route network 30.
The copy network 10 is configured as a nonblocking copy network for multicasting packet switching which is offered by Tony.T. LEE.
FIG. 2 illustrates an internal structure of the copy network which includes a running adder network 31, a dummy address encode 32, and a broadcast banyan network 33.
As a more detailed example, the configuration of the copy network 10 of FIG. 1 will be described as follows with reference to FIG. 2.
An incoming cell has a broadcast channel number(hereinafter, xe2x80x9cBCNxe2x80x9d) and a fan out(hereinafter, xe2x80x9cFOxe2x80x9d) header therein as illustrated in FIG. 2. The FO means the number of cells that is to be copied, that is, the number of multiconnections, and the BCN is a characteristic number representing multi-channel connections.
The maximum and minimum addresses are generated in the running adder network by the value of the FO, that is, the number of cells to be copied.
The above generation method means copying cells as many as the value of MAXA(Maximum Address)xe2x88x92MINA+1.
The cell copied as described above is translated to the destination addresses of the route network by the TNTs 20-1xcx9c20-n, the BCN, and a CI(Copy Identifier) illustrated in FIG. 1.
However, in order for the thusly configured conventional copy network to be configured as one switching system, a translation table and a translator as well as the route network are required, whereby hardware components are consumed greatly to thus increase the costs, and each of the components must be expanded in the case of an expansion for thus making the configuration complicated.
The present invention relates to an apparatus and a method for configuring a multicasting network in an ATM switching system and, more particularly, to an apparatus and a method for configuring a multicasting network in an Asynchronous Transfer Mode switching system in which cell copying and routing are performed using a space division switch, without using a translator and a translation table between a copy network and a route network compared to the conventional art, whereby the number of hardware components is reduced, and an expansion of the same is easily performed by the method of increasing the number of space switches during the expansion.